Early-onset pamidronate therapy may reduce disease activity in chronic nonbacterial osteomyelitis

Treatment with pamidronate appears to improve clinical and radiological disease activity in children categorized with extended chronic nonbacterial osteomyelitis (CNO), particularly after 1 year of treatment, a study has shown. However, some children present with active disease after 2 years of pamidronate use.

Fifty-one children were included, with a median follow-up of 4 years (interquartile range, 3–7). Of these, 32 had extended CNO and were treated in an early-onset 2-year pamidronate regimen.

Whole-body magnetic resonance imaging (WB-MRI) was performed among children with extended CNO at time of diagnosis (88 percent) and at years 1 (84 percent) and 2 (91 percent). A decline was seen in the total number of radiologically active lesions and number of spinal lesions per patient declined (p=0.01) during the first year.

Twelve of the 32 children (38 percent) presented with clinically inactive disease, but eight of them (67 percent) experienced clinical relapse. In 19 children with limited CNO, 10 (53 percent) had clinically inactive disease after 1 year and did not experience clinical relapse.

In this single-centre retrospective study, the authors included children fulfilling the Bristol Criteria for CNO and performed WB-MRI or local MRI at the time of diagnosis to assess radiological disease activity. Extended CNO in children was characterized as having multifocal or spinal bone inflammation and clinical disease activity not responding to nonsteroidal anti-inflammatory drugs. Clinical disease activity was examined annually.

“CNO is a sterile inflammatory bone disorder with an unpredictable disease course,” the authors said.